Aim. To investigate the impact of patient immune status on the severity of COVID-19. Materials and methods. The prospective study included 63 employees of the V.I. Kulakov NMRC for OG&P of Minzdrav of Russia with confirmed COVID-19. The patients were stratified into three groups based on the disease severity, including asymptomatic (group 1, n=17), mild (group 2, n=29), and moderate (group 3, n=17) form of COVID-19. On days 3–7 from the onset of the disease, peripheral venous blood samples were collected from the study subjects and tested for serum levels of anti-SARS-CoV-2 IgG antibodies and immune profile by ELISA. After day 20+, testing for serum levels of anti-SARS-CoV-2 IgG antibodies was repeated using ELISA. Results. Patients who had a higher BMI, blood group A(II), lower leukocyte and lymphocyte counts, higher relative monocyte count, changes in the immune profile in the form of a lower number of CD3 , CD3 CD8 , СD19 , CD19 CD5 , and phagocytic activity of neutrophils, developed more severe forms of COVID-19. They had severe clinical manifestations of the disease, and 100% of them developed antiviral immunity. Conclusion. This study identified several clinical, laboratory, and immune profile features that may be considered as predictive factors of severe COVID-19 and can be used in clinical practice to predict the clinical course of the disease. + + + + + +